1. Field of the Invention
The present invention relates to devices for preventing locking cylinders from freezing and, more particularly, to such devices that are easily added to existing installations of such locking cylinders.
2. Description of the Prior Art
Numerous devices have been developed to heat locking cylinders after they have become frozen, such as U.S. Pat. Nos. 3,192,359; 4,247,753; and 4,303,825. Since the thawing process can take time that can cause problems when one is in a hurry, a device to prevent a locking cylinder from freezing is preferable.
Typical devices to prevent locking cylinders from freezing are disclosed in U.S. Pat. Nos. 3,662,149 and 4,442,341 wherein PTC heating elements are embedded within heat-conductive, electrically insulative material and provide conductive heat to a rear portion or an underside of a locking cylinder. None of these devices provide conductive heat around a locking cylinder, convective heat, or radiant heat of any form, and do not include easily replaceable heating elements. These features can be beneficial to use. There is a need for a device that prevents locking cylinders from freezing that includes these features.